1. Field of the Invention
The present invention relates to a stator for an electric motor and a washing apparatus having the same, and more particularly, to a stator for an electric motor, which can reduce the waste of materials of a stator core and furthermore, assure the use of simplified equipment, and a washing apparatus having the same.
2. Background Art
Generally, examples of washing apparatuses include a washing machine for washing laundry and a drying machine for drying wet laundry by use of high-temperature air. Both the washing machine and the drying machine are provided with a drum in which laundry is washed or dried, the drum being rotated by a motor. More particularly, in a drum washing machine that is recently in the spotlight of consumers, after a detergent, wash water, and laundry are put into a drum, the drum is rotated upon receiving a drive force from a motor such that the laundry, received in the drum, can be washed by use of a frictional force between the drum and the laundry. The drum washing machine has less damage to the laundry, and prevents entangling of the laundry while achieving excellent laundry washing effects by pounding and rubbing.
Conventional drum washing machines are classified, on the basis of a driving manner thereof, into an indirect-connection type in which a drive force of a motor is indirectly transmitted to a drum via a belt wound on a motor pulley and a drum pulley, and a direct-connection type in which a rotor of a BLDC motor is directly connected to a drum to directly transmit a drive force of the motor to the drum. Here, in relation with the former indirect-connection type drum washing machine in which the drive force of the motor is indirectly transmitted via the belt wound on the motor pulley and the drum pulley, rather than being directly transmitted to the drum, there are problems in that the loss of energy occurs in the course of transmitting the drive force and a great amount of noise is generated in the transmission of power.
Therefore, to solve the above described problems of the conventional indirect-connection type drum washing machine, the use of the direct-connection type drum washing machine using a BLDC motor is expanding. Now, the configuration of a conventional direct-connection type drum washing machine will be described in brief with reference to FIG. 1.
FIG. 1 is a longitudinal sectional view illustrating the configuration of a conventional drum washing machine. The conventional drum washing machine comprises a tub 2 installed in a cabinet 1, and a drum 3 rotatably installed in the center of the tub 2. A motor is coupled to a rear side of the tub 2. Specifically, a stator 6 of the motor is fixed to a rear wall portion of the tub 2, and a rotor 5 of the motor is axially connected to the drum 3 by penetrating through the tub 2 while surrounding the stator 6.
Although not shown, a metallic tub supporter is interposed between the rear wall portion of the tub 2 and the stator 6. The tub supporter has approximately the same shape as the outer contour of the rear wall portion of the tub 2. Once the stator 6 is coupled to the rear wall portion of the tub 2, the tub supporter is fixed to the rear wall portion of the tub 2, so as to support the load of the stator 6 while maintaining the concentricity of the stator 6.
The cabinet 1 is provided, at a front side thereof, with a door 21, and a gasket 22 is installed between the door 21 and the tub 2. A hanging spring 23 is installed between an inner ceiling surface of the cabinet 1 and an outer top surface of the tub 2, to support the tub 2. Also, a friction damper 24 is installed between an inner bottom surface of the cabinet 1 and an outer lower surface of the tub 2, to alleviate vibrations of the tub 2 caused during a dehydrating operation.
FIG. 2 is a perspective view illustrating the outer appearance of the stator provided in the washing machine of FIG. 1, and FIG. 3 is a perspective view illustrating a dividable core DC used in the stator of FIG. 2. As shown in FIGS. 2 and 3, the conventional stator core takes the form of an assembly of unit cores, the unit cores being stacked one above another and connected with one another in a circumferential direction thereof. Each of the unit cores is formed by pressing an iron plate, and includes a base 150, a plurality of poles 151 formed along an outer periphery of the base 150, and a plurality of protrusions 500 formed along an inner periphery of the base 150, each protrusion 500 having a coupling hole 500a. In addition to providing the coupling holes 500a required to couple the stator 6 to the rear wall portion of the tub 2, the protrusions 500 support a fastening force of bolts through the coupling holes 500a. 
However, the above described conventional dividable core DC has several problems of, for example, the excessive loss of materials and a complicated manufacturing process. Specifically, in the manufacture of the dividable core DC, after each unit core is fabricated by pressing a single iron plate, a plurality of the fabricated unit cores have to be stacked one above another to form a core assembly. The stacked unit cores also have to be connected to one another in a circumferential direction thereof. With the above described press process of the unit cores, a large proportion of each iron plate is wasted, resulting in the excessive loss of materials. Further, due to the feet that the unit core is provided with the protrusions 500 at the opposite side of the poles 151, the amount of the iron plate required for the manufacture of the unit core increases, and the fabrication of the unit core is more complicated.
To solve the above described problems of the conventional dividable core, there has been developed a spiral core as shown in FIG. 4. The spiral core is formed by spirally winding each core iron plate and stacking a plurality of spirally wound core iron plates one above another.
As shown in FIG. 4, to form the conventional spiral core SC, two iron plates 11 are punched from a single electric steel plate 10. In the electric steel plate 10, specifically, the two iron plates 11 are included such that a pair of band-shaped bases 150 of the iron plates 11 face each other in a width direction of the spiral core SC and poles 151 protruding from the bases 150 are arranged alternately in two rows. In this way, if a plurality of iron plates 11 are prepared, the iron plates are rotated and spirally wound, respectively, and stacked one above another from the bottom to the top to have a multilayer structure.
Here, in the course of spirally rotating and winding the iron plates 11, to prevent the iron plates 11 from being unwound in an opposite direction of the rotating direction thereof or to prevent the respective stacked iron plates 11 from coming off the underneath iron plate 11, each pole 151 of the iron plates 11 is formed, at an upper surface thereof, with an engagement boss 154a, and at a lower surface thereof, with an engagement recess corresponding to the engagement boss 154a. Also, to reduce a winding stress applied to the iron plate 11 for the sake of facilitating the winding of the iron plate 11, the base 150 of the iron plate 11 is formed, at an inner periphery thereof, with vertical grooves 152 such that the vertical grooves 152 are located between the respective neighboring poles 151.
As described above, the iron plates 11 are punched, in two rows, from the electric steel plate 10, and the base 150 of each iron plate 11 has notches 150a having the same shape as that of distal ends of the poles 151 of the opposite iron plate 11. Each pole 151 of the iron plate 11 has ejector recesses 151d, to assure an easy separation of the punched two rows of the iron plates 11.
Once all the iron plates 11 are stacked one above another, rivets 153 are penetrated through holes perforated in the bases 150 of the iron plates 11, to couple the iron plates to one another by riveting. A winding beginning portion and a winding ending portion of each of the stacked iron plates 11 are bonded to predetermined positions of the respective contact bases 150 by welding.
The above described conventional spiral core has an advantage of eliminating the waste of materials because core iron plates, which are symmetrically arranged in two rows, are punched from a single electric steel plate. However, the punched core iron plates have a need for large-scale winding equipment.